Field of the Invention
The present invention relates to a grinding method for grinding a plate-shaped workpiece to a desired thickness while the thickness of the plate-shaped workpiece is measured.
Description of the Related Art
In a grinding process, a method is known wherein a plate-shaped workpiece is ground while the thickness thereof is measured by a height gauge of the contact type (for example, refer to Japanese Patent Laid-Open No. 2008-073785). In a height gauge of the contact type, a pair of contactors are contacted with an upper face of a plate-shaped workpiece and an upper face of a chuck table to detect the thickness of the plate-shaped workpiece from the difference in height between the contacting positions of the contactors. Further, as a grinding method of a bonded work configured from a plurality of plate-shaped workpieces, a method is known wherein the bonded work is ground while the thickness of the upper side work of a grinding target is measured by thickness measuring means of the contactless type (for example, refer to Japanese Patent Laid-Open No. 2008-264913). The thickness measuring means of the contactless type detects the thickness of a plate-shaped workpiece from the optical path difference of a laser beam reflected by upper and lower faces of the upper side work.
Also a method is known wherein a height gauge of the contact type and thickness measuring means of the contactless type are combined to measure the thickness of a plate-shaped workpiece while the plate-shaped workpiece is ground (for example, refer to Japanese Patent Laid-Open No. 2007-335458). According to this grinding method, upon rough grinding, the rough grinding amount is adjusted while the total thickness of a plate-shaped workpiece including the thickness of a protective tape is measured by the height gauge of the contact type. Then, upon finish grinding, the finish amount is controlled while only the thickness of the plate-shaped workpiece is measured by the thickness measuring means of the contactless type. Further, in addition to the grinding methods described above, also a method is known wherein the inclination of a chuck table with respect to grinding means is adjusted on the basis of the measured thickness of a plate-shaped workpiece to grind the plate-shaped workpiece with a uniform thickness (for example, refer to Japanese Patent Laid-Open No. 2013-119123).